Browsing by Author "Lagos, Daniel"
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- ItemInner mitochondrial membrane structure and fusion dynamics are altered in senescent human iPSC-derived and primary rat cardiomyocytes(Elsevier B.V., 2023) Morris, Silke; Busch, Karin B.; Molina Riquelme, Isidora; Barrientos, Gonzalo; Bravo, Francisco; Aedo, Geraldine; Gómez, Wileidy; Lagos, Daniel; Eisner Sagues Veronica Raquel; Verdejo, Hugo; Peischard, Stefan; Seebohm, Guiscard; Psathaki, Olympia E.Dysfunction of the aging heart is a major cause of death in the human population. Amongst other tasks, mitochondria are pivotal to supply the working heart with ATP. The mitochondrial inner membrane (IMM) ultrastructure is tailored to meet these demands and to provide nano-compartments for specific tasks. Thus, function and morphology are closely coupled. Senescent cardiomyocytes from the mouse heart display alterations of the inner mitochondrial membrane. To study the relation between inner mitochondrial membrane architecture, dynamics and function is hardly possible in living organisms. Here, we present two cardiomyocyte senescence cell models that allow in cellular studies of mitochondrial performance. We show that doxorubicin treatment transforms human iPSC-derived cardiomyocytes and rat neonatal cardiomyocytes in an aged phenotype. The treated cardiomyocytes display double-strand breaks in the nDNA, have ?-galactosidase activity, possess enlarged nuclei, and show p21 upregulation. Most importantly, they also display a compromised inner mitochondrial structure. This prompted us to test whether the dynamics of the inner membrane was also altered. We found that the exchange of IMM components after organelle fusion was faster in doxorubicin-treated cells than in control cells, with no change in mitochondrial fusion dynamics at the meso-scale. Such altered IMM morphology and dynamics may have important implications for local OXPHOS protein organization, exchange of damaged components, and eventually the mitochondrial bioenergetics function of the aged cardiomyocyte.
- ItemOPA1 disease-causing mutants perturb mitochondrial nucleoid cluster distribution(ELSEVIER, 2022) Eisner, Veronica; Macuada, Josefa; Vidal, Gonzalo; Molina-Riquelme, Isidora; Aedo, Geraldine; Lagos, Daniel; Perez, Nicolas; Rudge, Timothy; Cartes-Saavedra, Benjamin
- ItemOPA1 Modulates Mitochondrial Ca2+ Uptake Through ER-Mitochondria Coupling(FRONTIERS MEDIA SA, 2022) Cartes Saavedra, Benjamin; Macuada, Josefa; Lagos, Daniel; Arancibia, Duxan; Andres, Maria E.; Yu Wai Man, Patrick; Hajnoczky, Gyoergy; Eisner, VeronicaAutosomal Dominant Optic Atrophy (ADOA), a disease that causes blindness and other neurological disorders, is linked to OPA1 mutations. OPA1, dependent on its GTPase and GED domains, governs inner mitochondrial membrane (IMM) fusion and cristae organization, which are central to oxidative metabolism. Mitochondrial dynamics and IMM organization have also been implicated in Ca2+ homeostasis and signaling but the specific involvements of OPA1 in Ca2+ dynamics remain to be established. Here we studied the possible outcomes of OPA1 and its ADOA-linked mutations in Ca2+ homeostasis using rescue and overexpression strategies in Opa1-deficient and wild-type murine embryonic fibroblasts (MEFs), respectively and in human ADOA-derived fibroblasts. MEFs lacking Opa1 required less Ca2+ mobilization from the endoplasmic reticulum (ER) to induce a mitochondrial matrix [Ca2+] rise ([Ca2+](mito)). This was associated with closer ER-mitochondria contacts and no significant changes in the mitochondrial calcium uniporter complex. Patient cells carrying OPA1 GTPase or GED domain mutations also exhibited altered Ca2+ homeostasis, and the mutations associated with lower OPA1 levels displayed closer ER-mitochondria gaps. Furthermore, in Opa1(-/-) MEF background, we found that acute expression of OPA1 GTPase mutants but no GED mutants, partially restored cytosolic [Ca2+] ([Ca2+](cyto)) needed for a prompt [Ca2+](mito) rise. Finally, OPA1 mutants' overexpression in WT MEFs disrupted Ca2+ homeostasis, partially recapitulating the observations in ADOA patient cells. Thus, OPA1 modulates functional ER-mitochondria coupling likely through the OPA1 GED domain in Opa1(-/-) MEFs. However, the co-existence of WT and mutant forms of OPA1 in patients promotes an imbalance of Ca2+ homeostasis without a domain-specific effect, likely contributing to the overall ADOA progress.